Modern camera devices support an Auto Focusing (AF) detection function which is a function of automatically adjusting a focus. However, the AF detection function has various problems. For example, when a subject to be focused is partially hidden by another object located closer to a camera lens in comparison with the subject, it is difficult for a camera to detect the main subject through the AF detection function. Further, when a user photographs with a low light level, the camera cannot recognize a difference between the main subject and other objects and thus sometimes cannot detect the main subject through the AF detection function. Moreover, when the main subject is an object that absorbs infrared light, the camera cannot properly measure a distance between the main subject and the camera through the AF detection function. In addition, when the user photographs an object having a low contrast, for example, a white wall, sky or the like, the camera cannot detect a focus through the AF detection function.
When the user wants to photograph by using camera equipment, the user manually or automatically set the focus. In general, the focus is set to the object selected by the user in an automatic mode. It is preferable that the object is generally located within a small square of a center area of a frame, that is, a particular area of the frame. In another setting method, a camera apparatus temporarily provides a plurality of areas for a focus setting to the user and the user sets the focus by selecting one of the plurality of areas. Thereafter, the user can half press a shutter button of the camera apparatus to focus a lens on the selected object. Even though the frame leaves a position of the selected object, when the user maintains the action of half pressing the shutter button, it is difficult to re-focus. When the user more heavily presses the shutter button, an action follows of taking a picture in a state where the selected object is focused. As described above, the AF function of the camera apparatus requires close attention of the user.
The general AF function is performed by the camera apparatus based on a contrast value of an image input through the lens. When a scene or area used to focus does not have reasonable contrast, the AF can fail. Such a phenomenon sometimes occurs when photographing is performed in the dark or when large and flat planes having similar colors are photographed. Further, when the subject is not located in the center of the frame, performance of the AF function can have an error. When the subject, that is, the selected object is partially or entirely hidden by objects located closer to the camera apparatus, the camera apparatus cannot perform the AF function and the user should directly set the focus manually.